Introduction: Adherence and persistence to immunomodulatory therapies for multiple sclerosis (MS) plays an essential role in maximizing the treatment benefits and patient outcomes. The aim of this study was to evaluate medication adherence and persistence of patients with multiple sclerosis in Slovenia and assess the impact certain variables may have on them.
Methods: The study included patients, who began their treatment with disease-modifying drugs (DMDs) in years 2011 - 2014 and had at least one prescription fill of any medication after an observational window of 5 years. Patients that received a natalizumab prescription were excluded from the analysis. The analysis was conducted using AdhereR software. Adherence was assessed using the algorithm CMA5, using the method of proportion of days covered (PDC), together with ANOVA to evaluate the impact of various factors. Whilst assessing adherence we included DMD switches and followed patients from the first to last dispensing within the 5-year period. Patients were considered adherent if they had PDC > 80%. Persistence was defined as no evidence of switching from the first prescribed immunomodulatory drug or no treatment gap > 60 days and analyzed using Kaplan-Meier analysis. The impact of various factors on persistence was evaluated using the log-rank test.
Results: A total of 316 patients were followed for 5 years, with the average age of 43 years, of whom 70.8% were female. The average adherence in a 5-year period was 82,9 %, with 69,9 % of the 316 patients being adherent (PDC > 80%). Factors such as gender, age and region had no significant correlation with adherence and persistence. During the 5-year period it was found that persistence rate was 18,6 %. Persistence was 33,1 % with glatiramer acetate and 25,0 % with beta interferons (1a and 1b, subcutaneous and intramuscular applications), while persistence was lower with teriflunomide (11,1 %), fingolimod (31,2 %) and dimethyl fumarate (0%). The persistence with injectable DMDs (31,2 %) was significantly higher compared to oral DMDs (3,5 %). Nevertheless, when choosing individual therapy, it is necessary to consider other factors, including efficacy, safety, and patient suitability.
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